This application proposes a longitudinal follow-up of a multi-ethnic sample of 999 youth into young adulthood. Young adult assessments will include interview and questionnaire measurement of drug abuse, criminality, unsafe sexual behaviors, and other risk factors known to contribute to serious maladjustment including HIV/AIDS and psychological illness. This sample was originally recruited from 6th graders at three public schools. Youth and their families were randomized at the individual level to the Adolescent Transitions Program (ATP), a multilevel, family-centered intervention embedded within the operating system of the public school environment (Dishion &Kavanagh, 2003), or to a no treatment control group. Participating youth were originally assessed in 6th, 7th, and 8th grades using self-report surveys, peer nominations, teacher ratings, and school records, as well as self-report surveys in the 9th grade. Videotapes of observed family and peer interactions;a multi-agent assessment battery including youth, parent, and teacher reports;and youth court records were also collected. Target youth also were administered the CIDI diagnostic interview. The goal of this phase of research is to expand our understanding of the etiology of the onset and escalation of adolescent and young adult drug abuse and other related problem behaviors by accomplishing the following two objectives: (1) evaluate and report the patterns of engagement, mediation, and long-term effectiveness of the ATP intervention;and (2) refine and test an ecological model of drug abuse, problem behavior, HIV/AIDS risk behavior, and young adult psychopathology based on information obtained from the analyses related to the first objective. It is hypothesized that information gained about treatment effects, whether positive, negative, or neutral will serve to increase our collective understanding of the mechanisms related to poor early adult outcomes and our knowledge of who benefits from prevention programs such as the ATP and who does not.